A variety of optoelectronic devices are packaged devices which include a photodetector (PD) and at least one light source that are operated under a vacuum. Conventional MFAC and MFAM packages include a vertically stacked structure inside a package material including a bottom die as a support having electrical traces and at least one light source (e.g., a laser die such as a vertical-cavity surface-emitting laser (VCSEL)) mounted thereon, a first cavity die on the bottom die providing a cavity over the light source, and an optics die on the first cavity die. The electrical traces on the bottom die connect an external driver which drives the light source and includes traces for a resistive heater, such as to provide heat to heat the light source die to a temperature above 50° C., for example to a temperature between 60° C. and 80° C. A second cavity die is on a sealing die that is on the optics die, and a photodetector (PD) die is in a location to be coupled to receive the light originating from the light source. The package is a vacuum sealed package.